import {
    BufferGeometry,
    FileLoader,
    Float32BufferAttribute,
    Group,
    LineBasicMaterial,
    LineSegments,
    Loader,
    Material,
    Mesh,
    MeshPhongMaterial,
    Points,
    PointsMaterial,
    Vector3,
    Color
} from 'three';

// o object_name | g group_name
const _object_pattern = /^[og]\s*(.+)?/;
// mtllib file_reference
const _material_library_pattern = /^mtllib /;
// usemtl material_name
const _material_use_pattern = /^usemtl /;
// usemap map_name
const _map_use_pattern = /^usemap /;
const _face_vertex_data_separator_pattern = /\s+/;

const _vA = new Vector3();
const _vB = new Vector3();
const _vC = new Vector3();

const _ab = new Vector3();
const _cb = new Vector3();

const _color = new Color();

function ParserState() {

    const state = {
        objects: [],
        object: {},

        vertices: [],
        normals: [],
        colors: [],
        uvs: [],

        materials: {},
        materialLibraries: [],

        startObject: function(name, fromDeclaration) {

            // If the current object (initial from reset) is not from a g/o declaration in the parsed
            // file. We need to use it for the first parsed g/o to keep things in sync.
            if (this.object && this.object.fromDeclaration === false) {

                this.object.name = name;
                this.object.fromDeclaration = (fromDeclaration !== false);
                return;

            }

            const previousMaterial = (this.object && typeof this.object.currentMaterial === 'function' ? this.object.currentMaterial() : undefined);

            if (this.object && typeof this.object._finalize === 'function') {

                this.object._finalize(true);

            }

            this.object = {
                name: name || '',
                fromDeclaration: (fromDeclaration !== false),

                geometry: {
                    vertices: [],
                    normals: [],
                    colors: [],
                    uvs: [],
                    hasUVIndices: false
                },
                materials: [],
                smooth: true,

                startMaterial: function(name, libraries) {

                    const previous = this._finalize(false);

                    // New usemtl declaration overwrites an inherited material, except if faces were declared
                    // after the material, then it must be preserved for proper MultiMaterial continuation.
                    if (previous && (previous.inherited || previous.groupCount <= 0)) {

                        this.materials.splice(previous.index, 1);

                    }

                    const material = {
                        index: this.materials.length,
                        name: name || '',
                        mtllib: (Array.isArray(libraries) && libraries.length > 0 ? libraries[libraries.length - 1] : ''),
                        smooth: (previous !== undefined ? previous.smooth : this.smooth),
                        groupStart: (previous !== undefined ? previous.groupEnd : 0),
                        groupEnd: -1,
                        groupCount: -1,
                        inherited: false,

                        clone: function(index) {

                            const cloned = {
                                index: (typeof index === 'number' ? index : this.index),
                                name: this.name,
                                mtllib: this.mtllib,
                                smooth: this.smooth,
                                groupStart: 0,
                                groupEnd: -1,
                                groupCount: -1,
                                inherited: false
                            };
                            cloned.clone = this.clone.bind(cloned);
                            return cloned;

                        }
                    };

                    this.materials.push(material);

                    return material;

                },

                currentMaterial: function() {

                    if (this.materials.length > 0) {

                        return this.materials[this.materials.length - 1];

                    }

                    return undefined;

                },

                _finalize: function(end) {

                    const lastMultiMaterial = this.currentMaterial();
                    if (lastMultiMaterial && lastMultiMaterial.groupEnd === -1) {

                        lastMultiMaterial.groupEnd = this.geometry.vertices.length / 3;
                        lastMultiMaterial.groupCount = lastMultiMaterial.groupEnd - lastMultiMaterial.groupStart;
                        lastMultiMaterial.inherited = false;

                    }

                    // Ignore objects tail materials if no face declarations followed them before a new o/g started.
                    if (end && this.materials.length > 1) {

                        for (let mi = this.materials.length - 1; mi >= 0; mi--) {

                            if (this.materials[mi].groupCount <= 0) {

                                this.materials.splice(mi, 1);

                            }

                        }

                    }

                    // Guarantee at least one empty material, this makes the creation later more straight forward.
                    if (end && this.materials.length === 0) {

                        this.materials.push({
                            name: '',
                            smooth: this.smooth
                        });

                    }

                    return lastMultiMaterial;

                }
            };

            // Inherit previous objects material.
            // Spec tells us that a declared material must be set to all objects until a new material is declared.
            // If a usemtl declaration is encountered while this new object is being parsed, it will
            // overwrite the inherited material. Exception being that there was already face declarations
            // to the inherited material, then it will be preserved for proper MultiMaterial continuation.

            if (previousMaterial && previousMaterial.name && typeof previousMaterial.clone === 'function') {

                const declared = previousMaterial.clone(0);
                declared.inherited = true;
                this.object.materials.push(declared);

            }

            this.objects.push(this.object);

        },

        finalize: function() {

            if (this.object && typeof this.object._finalize === 'function') {

                this.object._finalize(true);

            }

        },

        parseVertexIndex: function(value, len) {

            const index = parseInt(value, 10);
            return (index >= 0 ? index - 1 : index + len / 3) * 3;

        },

        parseNormalIndex: function(value, len) {

            const index = parseInt(value, 10);
            return (index >= 0 ? index - 1 : index + len / 3) * 3;

        },

        parseUVIndex: function(value, len) {

            const index = parseInt(value, 10);
            return (index >= 0 ? index - 1 : index + len / 2) * 2;

        },

        addVertex: function(a, b, c) {

            const src = this.vertices;
            const dst = this.object.geometry.vertices;

            dst.push(src[a + 0], src[a + 1], src[a + 2]);
            dst.push(src[b + 0], src[b + 1], src[b + 2]);
            dst.push(src[c + 0], src[c + 1], src[c + 2]);

        },

        addVertexPoint: function(a) {

            const src = this.vertices;
            const dst = this.object.geometry.vertices;

            dst.push(src[a + 0], src[a + 1], src[a + 2]);

        },

        addVertexLine: function(a) {

            const src = this.vertices;
            const dst = this.object.geometry.vertices;

            dst.push(src[a + 0], src[a + 1], src[a + 2]);

        },

        addNormal: function(a, b, c) {

            const src = this.normals;
            const dst = this.object.geometry.normals;

            dst.push(src[a + 0], src[a + 1], src[a + 2]);
            dst.push(src[b + 0], src[b + 1], src[b + 2]);
            dst.push(src[c + 0], src[c + 1], src[c + 2]);

        },

        addFaceNormal: function(a, b, c) {

            const src = this.vertices;
            const dst = this.object.geometry.normals;

            _vA.fromArray(src, a);
            _vB.fromArray(src, b);
            _vC.fromArray(src, c);

            _cb.subVectors(_vC, _vB);
            _ab.subVectors(_vA, _vB);
            _cb.cross(_ab);

            _cb.normalize();

            dst.push(_cb.x, _cb.y, _cb.z);
            dst.push(_cb.x, _cb.y, _cb.z);
            dst.push(_cb.x, _cb.y, _cb.z);

        },

        addColor: function(a, b, c) {

            const src = this.colors;
            const dst = this.object.geometry.colors;

            if (src[a] !== undefined) dst.push(src[a + 0], src[a + 1], src[a + 2]);
            if (src[b] !== undefined) dst.push(src[b + 0], src[b + 1], src[b + 2]);
            if (src[c] !== undefined) dst.push(src[c + 0], src[c + 1], src[c + 2]);

        },

        addUV: function(a, b, c) {

            const src = this.uvs;
            const dst = this.object.geometry.uvs;

            dst.push(src[a + 0], src[a + 1]);
            dst.push(src[b + 0], src[b + 1]);
            dst.push(src[c + 0], src[c + 1]);

        },

        addDefaultUV: function() {

            const dst = this.object.geometry.uvs;

            dst.push(0, 0);
            dst.push(0, 0);
            dst.push(0, 0);

        },

        addUVLine: function(a) {

            const src = this.uvs;
            const dst = this.object.geometry.uvs;

            dst.push(src[a + 0], src[a + 1]);

        },

        addFace: function(a, b, c, ua, ub, uc, na, nb, nc) {

            const vLen = this.vertices.length;

            let ia = this.parseVertexIndex(a, vLen);
            let ib = this.parseVertexIndex(b, vLen);
            let ic = this.parseVertexIndex(c, vLen);

            this.addVertex(ia, ib, ic);
            this.addColor(ia, ib, ic);

            // normals

            if (na !== undefined && na !== '') {

                const nLen = this.normals.length;

                ia = this.parseNormalIndex(na, nLen);
                ib = this.parseNormalIndex(nb, nLen);
                ic = this.parseNormalIndex(nc, nLen);

                this.addNormal(ia, ib, ic);

            } else {

                this.addFaceNormal(ia, ib, ic);

            }

            // uvs

            if (ua !== undefined && ua !== '') {

                const uvLen = this.uvs.length;

                ia = this.parseUVIndex(ua, uvLen);
                ib = this.parseUVIndex(ub, uvLen);
                ic = this.parseUVIndex(uc, uvLen);

                this.addUV(ia, ib, ic);

                this.object.geometry.hasUVIndices = true;

            } else {

                // add placeholder values (for inconsistent face definitions)

                this.addDefaultUV();

            }

        },

        addPointGeometry: function(vertices) {

            this.object.geometry.type = 'Points';

            const vLen = this.vertices.length;

            for (let vi = 0, l = vertices.length; vi < l; vi++) {

                const index = this.parseVertexIndex(vertices[vi], vLen);

                this.addVertexPoint(index);
                this.addColor(index);

            }

        },

        addLineGeometry: function(vertices, uvs) {

            this.object.geometry.type = 'Line';

            const vLen = this.vertices.length;
            const uvLen = this.uvs.length;

            for (let vi = 0, l = vertices.length; vi < l; vi++) {

                this.addVertexLine(this.parseVertexIndex(vertices[vi], vLen));

            }

            for (let uvi = 0, l = uvs.length; uvi < l; uvi++) {

                this.addUVLine(this.parseUVIndex(uvs[uvi], uvLen));

            }

        }

    };

    state.startObject('', false);

    return state;

}

//

class OBJLoader extends Loader {

    constructor(manager) {

        super(manager);

        this.materials = null;

    }

    load(url, onLoad, onProgress, onError) {

        const scope = this;

        const loader = new FileLoader(this.manager);
        loader.setPath(this.path);
        loader.setRequestHeader(this.requestHeader);
        loader.setWithCredentials(this.withCredentials);
        loader.load(url, function(text) {

            try {

                onLoad(scope.parse(text));

            } catch (e) {

                if (onError) {

                    onError(e);

                } else {

                    console.error(e);

                }

                scope.manager.itemError(url);

            }

        }, onProgress, onError);

    }

    setMaterials(materials) {

        this.materials = materials;

        return this;

    }

    parse(text) {

        const state = new ParserState();

        if (text.indexOf('\r\n') !== -1) {

            // This is faster than String.split with regex that splits on both
            text = text.replace(/\r\n/g, '\n');

        }

        if (text.indexOf('\\\n') !== -1) {

            // join lines separated by a line continuation character (\)
            text = text.replace(/\\\n/g, '');

        }

        const lines = text.split('\n');
        let result = [];

        for (let i = 0, l = lines.length; i < l; i++) {

            const line = lines[i].trimStart();

            if (line.length === 0) continue;

            const lineFirstChar = line.charAt(0);

            // @todo invoke passed in handler if any
            if (lineFirstChar === '#') continue;

            if (lineFirstChar === 'v') {

                const data = line.split(_face_vertex_data_separator_pattern);

                switch (data[0]) {

                    case 'v':
                        state.vertices.push(
                            parseFloat(data[1]),
                            parseFloat(data[2]),
                            parseFloat(data[3])
                        );
                        if (data.length >= 7) {

                            _color.setRGB(
                                parseFloat(data[4]),
                                parseFloat(data[5]),
                                parseFloat(data[6])
                            ).convertSRGBToLinear();

                            state.colors.push(_color.r, _color.g, _color.b);

                        } else {

                            // if no colors are defined, add placeholders so color and vertex indices match

                            state.colors.push(undefined, undefined, undefined);

                        }

                        break;
                    case 'vn':
                        state.normals.push(
                            parseFloat(data[1]),
                            parseFloat(data[2]),
                            parseFloat(data[3])
                        );
                        break;
                    case 'vt':
                        state.uvs.push(
                            parseFloat(data[1]),
                            parseFloat(data[2])
                        );
                        break;

                }

            } else if (lineFirstChar === 'f') {

                const lineData = line.slice(1).trim();
                const vertexData = lineData.split(_face_vertex_data_separator_pattern);
                const faceVertices = [];

                // Parse the face vertex data into an easy to work with format

                for (let j = 0, jl = vertexData.length; j < jl; j++) {

                    const vertex = vertexData[j];

                    if (vertex.length > 0) {

                        const vertexParts = vertex.split('/');
                        faceVertices.push(vertexParts);

                    }

                }

                // Draw an edge between the first vertex and all subsequent vertices to form an n-gon

                const v1 = faceVertices[0];

                for (let j = 1, jl = faceVertices.length - 1; j < jl; j++) {

                    const v2 = faceVertices[j];
                    const v3 = faceVertices[j + 1];

                    state.addFace(
                        v1[0], v2[0], v3[0],
                        v1[1], v2[1], v3[1],
                        v1[2], v2[2], v3[2]
                    );

                }

            } else if (lineFirstChar === 'l') {

                const lineParts = line.substring(1).trim().split(' ');
                let lineVertices = [];
                const lineUVs = [];

                if (line.indexOf('/') === -1) {

                    lineVertices = lineParts;

                } else {

                    for (let li = 0, llen = lineParts.length; li < llen; li++) {

                        const parts = lineParts[li].split('/');

                        if (parts[0] !== '') lineVertices.push(parts[0]);
                        if (parts[1] !== '') lineUVs.push(parts[1]);

                    }

                }

                state.addLineGeometry(lineVertices, lineUVs);

            } else if (lineFirstChar === 'p') {

                const lineData = line.slice(1).trim();
                const pointData = lineData.split(' ');

                state.addPointGeometry(pointData);

            } else if ((result = _object_pattern.exec(line)) !== null) {

                // o object_name
                // or
                // g group_name

                // WORKAROUND: https://bugs.chromium.org/p/v8/issues/detail?id=2869
                // let name = result[ 0 ].slice( 1 ).trim();
                const name = (' ' + result[0].slice(1).trim()).slice(1);

                state.startObject(name);

            } else if (_material_use_pattern.test(line)) {

                // material

                state.object.startMaterial(line.substring(7).trim(), state.materialLibraries);

            } else if (_material_library_pattern.test(line)) {

                // mtl file

                state.materialLibraries.push(line.substring(7).trim());

            } else if (_map_use_pattern.test(line)) {

                // the line is parsed but ignored since the loader assumes textures are defined MTL files
                // (according to https://www.okino.com/conv/imp_wave.htm, 'usemap' is the old-style Wavefront texture reference method)

                console.warn('THREE.OBJLoader: Rendering identifier "usemap" not supported. Textures must be defined in MTL files.');

            } else if (lineFirstChar === 's') {

                result = line.split(' ');

                // smooth shading

                // @todo Handle files that have varying smooth values for a set of faces inside one geometry,
                // but does not define a usemtl for each face set.
                // This should be detected and a dummy material created (later MultiMaterial and geometry groups).
                // This requires some care to not create extra material on each smooth value for "normal" obj files.
                // where explicit usemtl defines geometry groups.
                // Example asset: examples/models/obj/cerberus/Cerberus.obj

                /*
                 * http://paulbourke.net/dataformats/obj/
                 *
                 * From chapter "Grouping" Syntax explanation "s group_number":
                 * "group_number is the smoothing group number. To turn off smoothing groups, use a value of 0 or off.
                 * Polygonal elements use group numbers to put elements in different smoothing groups. For free-form
                 * surfaces, smoothing groups are either turned on or off; there is no difference between values greater
                 * than 0."
                 */
                if (result.length > 1) {

                    const value = result[1].trim().toLowerCase();
                    state.object.smooth = (value !== '0' && value !== 'off');

                } else {

                    // ZBrush can produce "s" lines #11707
                    state.object.smooth = true;

                }

                const material = state.object.currentMaterial();
                if (material) material.smooth = state.object.smooth;

            } else {

                // Handle null terminated files without exception
                if (line === '\0') continue;

                console.warn('THREE.OBJLoader: Unexpected line: "' + line + '"');

            }

        }

        state.finalize();

        const container = new Group();
        container.materialLibraries = [].concat(state.materialLibraries);

        const hasPrimitives = !(state.objects.length === 1 && state.objects[0].geometry.vertices.length === 0);

        if (hasPrimitives === true) {

            for (let i = 0, l = state.objects.length; i < l; i++) {

                const object = state.objects[i];
                const geometry = object.geometry;
                const materials = object.materials;
                const isLine = (geometry.type === 'Line');
                const isPoints = (geometry.type === 'Points');
                let hasVertexColors = false;

                // Skip o/g line declarations that did not follow with any faces
                if (geometry.vertices.length === 0) continue;

                const buffergeometry = new BufferGeometry();

                buffergeometry.setAttribute('position', new Float32BufferAttribute(geometry.vertices, 3));

                if (geometry.normals.length > 0) {

                    buffergeometry.setAttribute('normal', new Float32BufferAttribute(geometry.normals, 3));

                }

                if (geometry.colors.length > 0) {

                    hasVertexColors = true;
                    buffergeometry.setAttribute('color', new Float32BufferAttribute(geometry.colors, 3));

                }

                if (geometry.hasUVIndices === true) {

                    buffergeometry.setAttribute('uv', new Float32BufferAttribute(geometry.uvs, 2));

                }

                // Create materials

                const createdMaterials = [];

                for (let mi = 0, miLen = materials.length; mi < miLen; mi++) {

                    const sourceMaterial = materials[mi];
                    const materialHash = sourceMaterial.name + '_' + sourceMaterial.smooth + '_' + hasVertexColors;
                    let material = state.materials[materialHash];

                    if (this.materials !== null) {

                        material = this.materials.create(sourceMaterial.name);

                        // mtl etc. loaders probably can't create line materials correctly, copy properties to a line material.
                        if (isLine && material && !(material instanceof LineBasicMaterial)) {

                            const materialLine = new LineBasicMaterial();
                            Material.prototype.copy.call(materialLine, material);
                            materialLine.color.copy(material.color);
                            material = materialLine;

                        } else if (isPoints && material && !(material instanceof PointsMaterial)) {

                            const materialPoints = new PointsMaterial({
                                size: 10,
                                sizeAttenuation: false
                            });
                            Material.prototype.copy.call(materialPoints, material);
                            materialPoints.color.copy(material.color);
                            materialPoints.map = material.map;
                            material = materialPoints;

                        }

                    }

                    if (material === undefined) {

                        if (isLine) {

                            material = new LineBasicMaterial();

                        } else if (isPoints) {

                            material = new PointsMaterial({
                                size: 1,
                                sizeAttenuation: false
                            });

                        } else {

                            material = new MeshPhongMaterial();

                        }

                        material.name = sourceMaterial.name;
                        material.flatShading = sourceMaterial.smooth ? false : true;
                        material.vertexColors = hasVertexColors;

                        state.materials[materialHash] = material;

                    }

                    createdMaterials.push(material);

                }

                // Create mesh

                let mesh;

                if (createdMaterials.length > 1) {

                    for (let mi = 0, miLen = materials.length; mi < miLen; mi++) {

                        const sourceMaterial = materials[mi];
                        buffergeometry.addGroup(sourceMaterial.groupStart, sourceMaterial.groupCount, mi);

                    }

                    if (isLine) {

                        mesh = new LineSegments(buffergeometry, createdMaterials);

                    } else if (isPoints) {

                        mesh = new Points(buffergeometry, createdMaterials);

                    } else {

                        mesh = new Mesh(buffergeometry, createdMaterials);

                    }

                } else {

                    if (isLine) {

                        mesh = new LineSegments(buffergeometry, createdMaterials[0]);

                    } else if (isPoints) {

                        mesh = new Points(buffergeometry, createdMaterials[0]);

                    } else {

                        mesh = new Mesh(buffergeometry, createdMaterials[0]);

                    }

                }

                mesh.name = object.name;

                container.add(mesh);

            }

        } else {

            // if there is only the default parser state object with no geometry data, interpret data as point cloud

            if (state.vertices.length > 0) {

                const material = new PointsMaterial({
                    size: 1,
                    sizeAttenuation: false
                });

                const buffergeometry = new BufferGeometry();

                buffergeometry.setAttribute('position', new Float32BufferAttribute(state.vertices, 3));

                if (state.colors.length > 0 && state.colors[0] !== undefined) {

                    buffergeometry.setAttribute('color', new Float32BufferAttribute(state.colors, 3));
                    material.vertexColors = true;

                }

                const points = new Points(buffergeometry, material);
                container.add(points);

            }

        }

        return container;

    }

}

export {
    OBJLoader
};